Recovery
Definition
The fraction of analyte that survives the extraction and clean-up workflow, measured by spiking a known amount of analyte into a blank matrix, running the full method and back-calculating. The accepted forensic window is 80 to 120 percent. A recovery of 45 percent is not necessarily wrong, but the method must correct for it through internal-standard normalisation, and the recovery figure must be on the validation report.
- Field
- Analytical chemistry, sample prep
- Accepted window
- 80 to 120 percent
- Measured via
- Spiked blank matrix, back-calculation
- Correction method
- Internal standard normalisation
Common questions
Why is a recovery of 45 percent not automatically a failed method?+
Low but consistent recovery can still produce accurate quantitative results if the method uses an internal standard that undergoes the same losses as the analyte, allowing the calculation to correct for the shortfall, provided the recovery figure itself is documented on the validation report.
What is the practical consequence if a method's recovery falls outside the 80 to 120 percent window without a correcting internal standard?+
Results risk systematic bias, either understating or overstating the true analyte concentration, which is why laboratories validate and document recovery for each method and matrix rather than assuming extraction efficiency is complete.
Related terms
- Bracketing Standards
- Calibration standards or quality control samples injected before, during and after a batch of case samples. They track instrument drift through the...
- Calibration Curve
- In RIA, a set of standards containing known concentrations of unlabelled analyte that are run alongside test samples. Bound radioactivity is measured...
- Certified Reference Material (CRM)
- A sample with one or more analyte concentrations established by an accredited body and traceable to a national metrology institute. NIST SRM...
- Extraction
- The first step in sample preparation. The analyte is pulled out of its original matrix (blood, urine, viscera, soil, paint chip) into...
- Internal Standard (IS)
- A compound chemically near-identical to the analyte, often a deuterated isotopologue (d3-morphine, d5-EDDP, d5-alprazolam, pyrene-d10), spiked into every sample at a known...
- Limit of Detection (LOD) and Limit of Quantitation (LOQ)
- LOD is the lowest concentration the instrument can reliably distinguish from blank, defined as three times the standard deviation of the blank...